Before the CISPR standards included the level of detail they do now about the test setup for emissions, we used the ANSI C63.4 standard for test setup. The latest version I have in our library is the 2001 version which says,
ANSI C63.4:2001, Section 5.2.2 Vertical Conducting Plane A tabletop device may be measured for AC powerline conducted emissions without a vertical conducting plane while maintaining the 80 cm EUT elevation specified in 6.2.1. However, in case of a dispute, ac powerline conducted emission measurements made on a tabletop device with a vertical, conducting plane in place shall take precedence. Also, interesting enough, CISPR11 (EN55011:2006) doesn’t even mention a vertical plane for conducted emissions testing. I interpreted it as allowing you to perform conducted emissions on an OATS using the same setup as Radiated Emissions which would include the 80 cm table and no vertical plane. It would appear as if the 40cm table is only required for options b) and c) below. CISPR11:2006, Section 7.1 Measurement of mains terminal disturbance voltage The measurement of the mains terminal disturbance voltage may be carried out: a) on the radiation test site with the equipment under test having the same configuration as used during the radiation measurement; b) above a metal ground plane which shall extend at least 0,5 m beyond the boundary of the equipment under test and have a minimum size of 2 m × 2 m; or c) within a screened room. Either the floor or one wall of the screened room shall act as the ground plane. Option a) shall be used where the test site contains a metal ground plane. In options b) and c) the test unit, if non-floor-standing, shall be placed 0,4 m from the ground plane. Floorstanding test units shall be placed on the ground plane, the point(s) of contact being insulated from the ground plane but otherwise consistent with normal use. All test units shall be at least 0,8 m from any other metal surface. Does EN55022 allow conducted emissions to be performed on an OATS without the vertical plane and with an 80 cm table? It sounds like it does as an optional configuration (I’m not an expert on EN55022). I would interpret a Semi-Anechoic chamber the same as an OATS. The Other Brian ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Spencer, David H Sent: Wednesday, September 23, 2009 7:50 AM To: Wan Juang Foo; [email protected]; [email protected] Subject: RE: Conducted emission measurements Tim, >From EN55022:2006 +A1: 2007 Section 9.5.2 Tabletop equipment arrangement 2) "...........(for example on an open area test site (OATS) or in a screened enclosure). The EUT shall be placed on a non-conductive table such that it is 0,4m above the horizontal ground reference plane." Regards, David Spencer EMC Engineer Xerox Corp. ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Wan Juang Foo Sent: Wednesday, September 23, 2009 1:46 AM To: [email protected]; [email protected] Cc: Wan Juang Foo Subject: Re: Conducted emission measurements Hello Tim, I may be missing. Is there such a 40 cm height? Here is my 5 ¢ worth. These are some of the the special provision for conducted emission testing: To meet EN 55011, I suppose since 1999?? the measurement may be carried out: - on the radiated emission test site (same EUT configuration) - above a metal ground plane which shall extend at least 50 cm beyond the boundary of the equipment under test and have a minimum size of 2m x 2m - within a screened room; either the floor or one wall of the screened room shall act as the vertical ground plane .. CISPR 22 since (1993) and Amendment 1 (1995) Table- top EUTis to be placed 40 cm from a vertical metal reference plane (e.g. a wall of a screened room/enclosure) "The EUT, where intended for table-top use, shall be placed 0,4 m from a vertical metal reference plane of at least 2 m by 2 m and shall be kept at least 0,8 m from any other metal surface or other ground-plane not being part of the EUT. If the measurement. is made in a screened enclosure, the distance of 0,4 m may be referred to one of the walls of the enclosure." Floor- standing EUT on a horizontal metal ground- plane, not in metallic contact with the ground- plane. Metal floor of a screened room may replace the reference ground- plane best regards, Tim Foo Expert Witness, EMC and Product Safety ECE, School of Engineering, http://www.np.edu.sg/ece/ DID: +65 6460 6143 Ngee Ann Polytechnic, 535 Clementi Road, Fax: +65 6467 1730 Singapore 599489 [email protected] wrote on 23/09/2009 06:06:05 AM: > Hello Group, > > I have a question about the conducted emission measurements > performed in a semi-anechoic chamber. > > CISPR 22 requires the use of a vertical ground plane when testing > tabletop EUTs, unless you mount your EUT on a non-conductive table > 40cm above the horizontal ground plane (instead of the traditional 80cm) > > I did not find a requirement for a vertical ground plane when > testing floorstanding equipment. If one opts to use the alternative > method of not using the vertical ground plane, can floorstanding > equipment also be tested without the vertical ground plane? The > horizontal ground plane is always present since that is the chamber floor. > > What are most labs using? We have the option of making a removable > vertical ground plane "wall" or mounting the equipment on a 40cm table. > > Thanks, > Tim Pierce > - ________________________________ NOTICE: This message may contain privileged/confidential information. If you are not the intended recipient of this email, please delete it immediately and notify the sender . _________________________ LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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